Typically, a static wheel load of a railcar is adjusted by: securing a gap between a frame and an air spring; and inserting a spacer (liner) into the gap or taking out the inserted spacer (liner) from the gap. To secure the gap between the frame and the air spring, a lower surface of the air spring needs to be separated from an upper surface of the frame by pushing up the air spring. Here, various technologies for pushing up the air spring have been proposed (PTLs 1 and 2). For example, according to a conventional art described in PTL 1, a pivot shaft (downward support projection) provided at a lower portion of the air spring is being slidably inserted into a receiving portion formed on the frame, and an elastic member is being interposed between the frame and the air spring. To secure the gap between the frame and the air spring in this conventional art, first, in a state where a carbody is supported by a supporting unit, such as a hydraulic jack, so as not to move downward, internal pressure of the air spring is reduced by removing air from the air spring. With this, the lower portion of the air spring is pushed up by elastic force of the elastic member, so that the gap is secured between the frame and the air spring.